Latent image printer



1966 J. 5. LINDERMAN 3,263,581

LATENT IMAGE PRINTER Filed June 1.8, 1963 3 Sheets-Sheet l W F l G. HECH. f 6' DRIVE -FILH 60 4 MICRO 99/00 swncu DETECTOR I TRIGGER GE LAMPLIFIER FORMER SUPPLY "s2 PULSE FLIP Q PULSE ucm snmn FLOP -sumzn DETECTOR some FILM 4 v JAMEQ STEPHENS LINDERMAN Manama/6 ATTORNEY INVENT OR :5 Sheets-Sheet 2 J. LINDERMAN LATENT IMAGE PRINTER llll INVENTOR JAMES STEPH ENS LINDERMAN ATTORNEY Aug. 2, 1966 Filed June 18. 1963 F I G. 3 mm FILI 'PLANE & PATH United States Patent 3,263,581 LATENT IMAGE PRINTER James Stephens Linderman, Wilmington, Del., asslgnor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed June 18, 1963, Ser. No. 288,767 4 Claims. (Cl. 95--1.1)

This invention relates to a film symbolizing device and, more particularly, it relates to a device for applying numbers or other symbols along the length of photographic film.

The editing of various scenes taken on photographic cine film into a completed motion picture requires that identification markings be placed beside the picture area so that wanted sections can be located swiftly and accurately. These identification marks have been standardized so that they usually consist of a 6- or 7-digit number that is'inserted between the perforations once per foot in an increasing or decreasing sequence. This identification means is called keynumbering by the industry.

Although numbers can be printed on the film by using an inked printing wheel, the necessity of drying the ink is such a serious limitation that it is seldom used. The method most commonly employed by the industry involves the optical exposure of numbers onto the film emulsion. This method, of course, requires development of the emulsion before the numbers are visible and, therefore, is referred to as LatentImage Keynumbering.

Several latent image keynumbering systems that are known in the art employ an external light source that illuminates mechanical counting wheels similar to an odometer. Reflected light is collected in such a manner that the image of the illuminated numerals is projected to a plane containing the film. This approach is frequently inadequate due to the difliculty in obtaining sufficiently high contrast between the bright numerals and the surrounding dark area and because of mechanical speed and wear limitations imposed by the counting wheels. In addition, these mechanical counting wheels generally employ a cog and tooth arrangement to advance the adjacent number disk when 9 or 99 comes up on the first disk. Such an arrangement usually results in drift or inaccurate positioning of the numbers causing them to appear out of line.

A satisfactory keynumbering system should be able to apply sharply defined numbers at a very high speed (e.g., 1000 ft./min.) at a precise location between perforations. Further, the system should have a high degree of reliability and require little supervision during operation.

These and other objects and advantages are accomplished in accordance with this invention which is particularly pointed out in the appended claims and is illustrated, in its preferred embodiments, in the accomemployed in the invention.

Referring now to the drawings, the keynumbering device illustrated operates on the principle of projecting numbering images on a moving film between the perforations thereof once per foot.

A flash lamp 10 is pro- 3,263,581 Patented August 2, 1966 ice vided which is located within stationary lamp housing 11 on the axis of three concentric rotary drums 12, 13 and 14. The surfaces of these drums are covered with an opaque material 12a, 13a, 13b and 14a as shown in FIG. 2 and a series of transparent numbers from 00 to 99 are produced thereon by etching through the opaque material. The numbers are positioned in a circumferential row on each drum, equally spaced from one another and occupying the entire circumference. The three rows are positioned closely adjacent to one another, so that conjointly they produce six-digit numbers, one of which is imaged as later described onto the film surface. Drum 12 is tightly fit onto collar 15 which freely rotates on bearings 16 and 17 and has spur gear 18 connected thereto. By engagement of the latter with gear reducing means 19, 20 and 21, drum 12 is driven from the main mechanical drive at such a rate that the surface numbers are advanced once per foot of film travel. Drums 13 and 14 are driven only by stepmotors 22 and 23 respectively through the gear drive arrangement depicted in FIG. 2. Step motor 22 is connected to end plate 24 (by means not shown) and directly drives spur gear 25 which together with spur gear 26 is mounted on shaft 27 in sleeve bearings 28 and 29. Drum 13 is tightly fit onto collars 30 and 31 which rotate freely about lamp housing 11 on bearings 32 and 33, respectively. Collar 31 has ring gear 34 attached thereto whose internal teeth are engaged by spur gear 26 thereby enabling step motor 22 to drive drum 13. Step motor 23 is also connected to end plate 24 (by means not shown) and directly drives internally toothed ring gear 35 which is attached to collar 36 which has drum 14 tightly fit thereon. The collar 36 freely rotates in bearings 37 and 38 about end block 39 which is held to light housing 11 and end plate 24 by bolt 40. End plate 24 together with keeper ring 41 mounted on light housing 11 hold the assembly together. The light housing 11 contains openings 42 and 43 and has a mirror-surface member 44 attached thereto by capscrew 45. The flashes of light from bulb 10 strike the surface of member 44 and are projected out through opening 43'onto the interiors of drums 12, 13

and 14. The latter are made of a translucent material but have opaque surfaces 12a, 13a and 13b except for the circumferential bands of numbers etched thereon. For this reason, the only light transmitted therethrough toward the film will be in the form of number images, and these are focussed upon the film by an optical system 52 to be described later. The light ray axis is depicted by the broken line arrows.

Step motors 22 and 23 are actuated only by 99/00 detectors 46 and 47 The latter are light sensitive phototransistors such as Photrans (manufactured by the Solid State Products Co.) which, when connected as shown in FIGURE 5, produce an output impulse responsive to light beams incident thereon. These light beams are created by placing apertures 48 and in surface 12a and aperture 49 in surface 13b of drums 12 and 13 in such a location that aperture 48 on drum 12 will be aligned with detector 46 permitting a light beam to strike the latter at such time that the number-image light beams directed at the film through drum 12 is at number 99 for an increasing series of numbers or at 00 for a decreasing series of numbers. This selection is made by mechanically repositioning detectors 46 and 47. Similarly, dr-um 13 contains aperture 49 and drum 12 contains aperture 80 which are so located that they will be in alignment with detector 47 permitting a light beam to strike the latter at the time both drums 12 and 13 are in positions at which number 99 is directed at the film from each drum for an increasing number sequence and number 00 is directed at the film for a decreasing number sequence. 1 5

The effect of such an arrangement is to direct light from bulb 10 off mirror surface 44 through Opening 43 at the drums 12, 13 and 14. At the beginning of operation, it is assumed that the drums are all positioned such that the numbers will be directed at the film from each drum. As the main mechanical drive commences to advance the film and rotate drum 12, the numbers 01 through 99 are consecutively focused at the film, while drums 13 and 14 remain unmoved and therefore permit only numbers 00 to be directed therefrom. When drum 12 has advanced to the position where number 99 is directed at the film, then aperture 48 is in alignment with detector 46. When bulb flashes detector 46 receives an impulse of light that is converted into an electrical signal thatadvances step mot-or 22 one position. The latter, on receipt of this impulse, advances drum 13 one position such that the number 01 is now being directed therefrom at the film. When both drums 12 and 13 are at their 99 position, detector 46 will actuate motor 22 as previously described and detector 47 will receive a light beam through apertures 49 and 80 which are now in alignment. Detector 47 will then actuate step motor 23 to advance drum 14 one position so that the number 01 is now being directed therefrom. The operation continues so that drum 12 is continuously revolved by the main mechanical drive at a rate of one number per foot of film travel. Drum 13 is advanced one number per complete revolution of drum 12 and drum 14 is advanced one number per complete revolution of drum 13.

Referring now specifically to FIGS. 3 and 4, the symbol projecting device depicted in FIG. 2 is located within housing 50 being fastened thereto by capscrew 51 which engages the end plate 24. The number-images are projected out through optical system 52 which is equipped with a shutter 53 and two lenses and focussed upon the film plane shown. The 99/00 detectors 46 and 47 are mounted to the housing 50 as shown; they are so mounted that they may be shifted in the direction tangential to the drums the distance of one number for reasons to be explained hereafter. The housing also contains printed circuit cards 54 (containing the flash trigger amplifier) and 55 (containing the 99/00 detector circuits); these electronic components are shown in FIG. 5.

Housing 50 has four openings 73, two being located on each of the two vertical faces. One on each face is opposite gear 18, such that gear 21 is admitted through the housing for meshing with gear 18, and such that gear 58, the purpose of which will be explained later, is admitted to mesh with gear 59, when the housing is turned 180. The other opening on each face is positioned to admit gear 58 when gear 21 is meshed with gear 18 and, in the 180 position, to admit gear 21 when gear 58 is meshed with gear 59.

While the device has been described above in connection with numbering film in ascending order, it can also be used to number the film in descending order. For example, housing 50 is releasably held in place with contact between gears 21 and 18, on V-rails 56 and 57 for numbering in ascending order as shown on FIGURE 3.

For numbering in descending order, the housing 50 is turned around 180 so that gear 58 turns spur gear 18 through idler gear 59. The latter may be suitably supported by means readily apparent to one skilled in the art but omitted from the drawings for the sake of clarity. This shift in operation will have the effect of rotating drum 12 in the opposite direction so that the number images are projected in descending order (i.e., from 99 downward). With this type of operation the detectors 46 and 47 must be shifted as described above so that the actuation of the step motors will properly occur when drum 12 is aligned for projection of number 00 (rather than for projection of number 99 as in the case for numbering in ascending order). Simultaneously with reversal of housing 50, the direction of rotation of step motors is switched automatically as described below.

The housing also carries two electrical terminal sets in the form of plugs 71 and 72, one of which meshes with a receptacle 70 carried on the face of the machine from which support and alignment rails 56 and 57 project. In one of the two positions of housing 50, plug 71 is in use, carrying power and signal to the components within housing 50. In the other position, plug 72 is in use. The wiring to the plugs from the stepping motors, and the wiring associated with the receptacle 70 is arranged so that reversal of housing 50 causes reversal of the direction of rotation of the stepping motors.

An important aspect of the invention is the means by which the flash lamp 10 is actuated. A microswitch 60 is mechanically actuated by cam 61 connected to the main mechanical drive in such a manner that switch 60 produces an electrical output once per foot of film travel. However, this impulse being mechanically produced is not precise enough to be used alone to trigger the flash lamp 10 such that the flashes could be well coordinated with respect to the perforations of the film. For this reason a perforation synchronization detector 62 is provided which produces an impulse responsive to the pulses of light that are received from a light source directed through the moving perforations of the film. Specifically, the system employs a photodetector 62 beneath the perforation track of the film and a spot of light directed at the track from the opposite side. When a perforation passes, the light is allowed to reach the detector; between perforations light is blocked from the detector. Detector 62 and pulse shaper 81 generate an electrical signal whose voltage is in one of two states depending on whether light is blocked by the film or passed by the perforations. This waveform is used to synchronize the flashing of lamp 10 as described below. A flip flop circuit 63 is provided which receives the pulse from the microswitch 60 at the rate of once per foot of film travel. This pulse, however, can only be released from the flip flop upon receipt of the synchronizing pulse from the perforation synchronization detector 62. In this manner the output from the flip flop circuit is regulated both with respect to film travel and location of perforations. The flash lamp 10 is a gaseous discharge lamp which has a high voltage impressed thereon. The lamp and its trigger circuitry is a commercial unit of which Model FX-31 made by Edgerton, Germeshausen, & Grier, Inc., Boston, Massachusetts, is an example. The voltage on the lamp is maintained just beneath the threshold value at which the gas will ionize so that firing is only accomplished when the additional voltage pulse is received from the flash trigger circuit 54 via pulse transformer 64. In this way the illumination of the flash lamp 10 is regulated by the output of the flip flop circuit 63 with the result that numbers are directed at the film in precisely the proper locations between the perforations.

Specifically, the output pulse from flip flop 63 is directed into housing 50 through receptacles 71 or 72 to flash trigger circuit 54. This input pulse is amplified by transistor A and coupled to a pulse amplifier consisting of fourlayer diodes B and C. These diodes (similar to Type 4E20, manufactured by Shockley Semiconductor Co.) re main in the nonconducting or high-impedance state until the input pulse from amplifier A causes the voltage across diode B to exceed 20 volts. At this time, diode B switches to a low-impedance and simultaneously diode C switches to a low impedance causing a positive voltage pulse to be applied to pulse transformer 64 through coupling capacitor D. Shortly after the pulse has been coupled to the pulse transformer diodes B & C return to the high-impedance state so that the circuit is ready for the next flash trigger. Pulse transformer 64 converts the 28 v. flash trigger pulse to a pulse several hundred volts in amplitude such that the arc in the flash lamp can be initiated.

The 99/00 detectors 46 and 47 and the 99/00 detector circuit card 55 contain the electronic circuitry needed to provide an electrical pulse to stepping motors 22 and 23. In both cases light from lamp is allowed to fall on the 99/00 detector when the rotating drums 12 and 13 are properly oriented. This light flash causes detector 46 to change from a high-impedance state to a low-impedance state. Energy is then allowed to flow through the detector to the stepping motor 22. Once detector 46 has reached its low-impedance state, it remains there until an external pulse generating circuit supplies suflicient power to reverse the current flow through the detector. This external pulse generation is accomplished by four-layer diode F similar to diodes B and C above. Upon initiation of power flow to stepping motor 22, voltage slowly rises across the fourlayer diode. This diode remains in the high-impedance state until the applied voltage exceeds v. At this time,

it breaks down to a low impedance. The resulting voltage pulse is coupled through capacitor 89 to the 99/00 detector 46 reversing its current and returning it to the highimpedance state. Current through four-layer diode F decreases exponentially until it is less than the required holding current of the device and then the diode returns to its high-impedance state. The cut off of detector 47 is similarly controlled by 4-layer diode E.

Diodes 82 and 83 serve to ground reverse-voltage pulses from the inductive kick of the stepping motor windings at the moment of switching off the detectors 46 and 47. Resistors 84, S5, 86 and 87 together with capacitors 88, 89, 90 and 91 regulate the rate of voltage buildup to shut off detectors 46 and 47.

The invention overcomes the inherent disadvantages of other keynumbering systems. The use of transparent number masks of cylindrical form (i.e., the drums) with a light source mounted on the cylinder axis completely eliminates background exposure around the number and maintains high contrast. The high optical efiiciency of this transmission system compared with existing methods, allows use of a flash lamp with low energy output, fast duration, and long life. This eliminates the blurring obtained from longer exposures and results in a simultaneous improvement in reliability.

The flash of the light source must be precisely synchronized with the location of the film perforations so that the numbers remain centered. At 1000 ft./mm., of film travel this synchronization must be maintained within il00 s. Previous systems have used electrical breaker points on sprocketed film rollers to provide synchronization. This approach is not precise enough for proper number appearance and results in extremely difficult maintenance and frequent failure. In the present system, the separate optical detector system provides location information within 10/13. This optical-electronic unit detects the presence or absence of a perforation and generates from this an accurate position synchronization pulse.

What is claimed is:

1. In a device for symbolizing a perforated film in a desired relationship with respect to the perforations comprising means for continuously moving said film past said device, and a flashing light source for projecting a series of symbols along said film, the improvement which comprises means for generating a flash impulse for actuating said light source responsive to film movement in combination with detector means for coordinating perforation passage with release of the flash impulse so as to occur only at a space between perforations.

2. A device for creating a series of symbol latent images in a precise location along the perforation track of a lightsensitive photographic film which comprises means for moving said film past said device, first and second drums, the surfaces of which are substantially opaque, each surface having a circumferential series of translucent symbols located thereon, said first drum having a specific translucent aperture on its surface to pass a light beam once during a sequence of said symbols, a flashing light source located within said drums, means for driving said first drum in synchronization with said film movement, a step motor for driving said second drum, means for actuating said step motor upon receipt of a light beam emanating from said light source through said specific aperture, and means for generating a flash impulse for actuating said light source responsive to film movement in combination with detector means for coordinating perforation passage with release of the flash impulse so as to occur only at a space between perforations.

3. A device as defined in claim 2 where said flash impulse generating means comprises means for signalling film passage, means for signalling film perforation passage and coordinating means to generate said flash impulse after comparing both of said passage signals to insure the absence of a perforation.

4. In a device for symbolizing a perforated film comprising means to move said film, counter means and means to project said counter symbols upon said film the improvement which comprises a first and second drum, the surfaces of which are substantially opaque, each surface having a circumferential series of translucent symbols located thereon, said first drum having a specific translucent aperture on its surface, a light source located within said drums, means for driving said first drum in relation to the passage of said perforated film, perforation sensing means for signalling the passage of a film perforation, means for signalling the passage of a selected length of film, and means for coordinating said perforation and said length signalling means to energize said light source.

References Cited by the Examiner UNITED STATES PATENTS 1,948,319 2/1934 Spence 95-1.l 2,302,001 11/1942 Bryce 23 5-133 2,490,338 12/1949 Marin 95-l.1 2,652,754 9/1953 Dedek 95--1.l 2,785,859 3/1957 Steinberg 235-133 2,945,624 7/1960 Nicolaus 235l33.5

JOHN M. HORAN, Primary Examiner. 

1. IN A DEVICE FOR SYMBOLIZING A PERFORATED FILM IN A DESIRED RELATIONSHIP WITH RESPECT TO THE PERFORATIONS COMPRISING MEANS FOR CONTINUOUSLY MOVING SAID FILM PAST SAID DEVICE, AND A FLASHING LIGHT SOURCE FOR PROJECTING A SERIES OF SYMBOLS ALONG SAID FILM, THE IMPROVEMENT WHICH COMPRISES MEANS FOR GENERATING A FLASH IMPULSE FOR ACTUATING SAID LIGHT SOURCE RESPONSIVE TO FILM MOVEMENT IN COMBINATION WITH DETECTOR MEANS FOR COORDINATING PERFORATION PASSAGE WITH RELEASE OF THE FLASH IMPULSE SO AS TO OCCUR ONLY AT A SPACE BETWEEN PERFORATIONS. 